Abstract
In this study, we have examined the decomposition speed of the mud-stones of Kobe group (Miocene) by the water content variations, Atterberg limits of the decomposed materials and the mineral composition.
The mud-stones are mainly formed of the following minerals; quartz, decomposed feldspar, montmorillonite, kaolinite, hydrated biotite, clinoptilolite and mordenite, and it's belong to the zone of clinoptilolite, mordenite and montmorillonite. The mud-stones, commonly, contain montmorillonite, so they have a high swelling potential and, without difficulty, produce a fine grain materials by the weathering, and a weathered soil of those mud-stones make a high active clay soil.
